This invention relates to fasteners to close a door and more particularly to fasteners which will not open in a fire.
1. Description of the Prior Art
he present invention is an improvement on a structure such as shown, for example in U.S. Pat. No. 4,003,593 to Wilzig et al. The Wilzig invention is limited to a push door latch opener lever that is vertically positioned unlike the present invention. In some physical situations it is advantageous to mount a door opener horizontally, as can be done with the present invention. A further advantage to the present invention is that, unlike the Wilzig invention, the present invention directly acts on the operating lever in the case of a fire. By contrast the Wilzig invention interferes directly with the operation of the push lever itself.
2. Summary of the Invention
A push door opening mechanism is disclosed for use where protection from fire is sought. In operation the push handle causes an operating lever to rotate within the door opener. The operating lever pulls a bolt which allows the door to open. This operating lever is mechanically biased to a return position. When in the return position, a cavity in the operating lever is positioned adjacent to a locking pin. That locking pin is held in the base plate and is longer than the depth of the cavity in the operating lever. The locking pin is also mechanically biased to move into the cavity. Once positioned in the cavity, the rotation of the operating lever is jammed because the locking pin is partially in the operating lever and partially held rigid in the base plate. However, during normal operation, the locking pin is retained out of the cavity by a fusible link pin. The link pin is made of a low melting point material and is in intimate contact with the base plate. During a fire the base plate becomes hot, causing the link pin to melt which frees the locking pin. The locking pin then moves into the cavity in the operating lever and jams the push door opener.